And why have you used 84 plates?

The thing about scientific protocols is that they are meant to be exact and precise. Every step must be explained concisely and there should be a reason for all the methodology.

For example, for every protocol you use, you should be able to answer random questions about why you did what you did at each step. Why was the bacteria incubated for four hours? Why was the temperature kept at 50 degrees? Why was the product stored on ice?

The answers to these questions should be sensible and scientific. Temperatures, amounts and incubation's are used to optimise reactions. Every step should be planned to get the best possible result in the most efficient way.

At the moment, we're growing phages on agar plates. At one stage of the protocol, we use exactly 84 plates to grow them. Two of the plates are controls and four are for dilutions but the fact remains that every time we use exactly 84 plates, no matter what we're doing.

The answer (as can probably be guessed) is not scientific in the least. Science is not a cold and clinical organised space, no matter how much scientists want it to be. It is a wild and crazy world full of human error and things going random and even more human error. The problems are not just scientific, they are also spacial and temporal; incubators are only so big, parts of the lab are only open during certain hours.

And the big jars we use for incubating will only physically fit 42 plates. We've tried to stuff more in but the lids won't shut. And while we have three of them in total the incubator is quite small and only fits two at a time.

42 x 2 = 84

Which wouldn't seem so bad if it weren't for the dilutions and the controls, because once you've put them in there's only room for 39 plates of actual phage sample per jar. 42 is at least a nice round number, but a protocol always looks a bit odd if it starts with the phrase '39 plates were taken...' It begs the question, 'why 39?' and the answer is, scientifically, faintly embarrassing.

Science would be a lot more precise if the world stopped getting in the way.

But far less fun =D